Use the Internet Archive to download Level 1 only. If you finish it and still want to learn Russian, buy Level 2 from Simon & Schuster (or check your library) to support the creators. The archive link is a trial, not a permanent solution.
Practical tips for getting the most from Pimsleur-style learning pimsleur russian internet archive link
However, the legal landscape is nuanced: Use the Internet Archive to download Level 1 only